Process of influencing the color of tobacco leaves



Patented Dec. 10, 1940 PATENT OFFICE PROCESS OF INFLUENCING THE COLOR OF TOBACCO LEAVES Georg Pfuetzer and burgerhof, Germany,

Hermann Losch, Lim

assignors to I. G. Farbenindustrie Aktiengesellschaft, Frankfort-on-the- Main, Germany No Drawing. Application September 23,1936, Se-

rial No. 102,158.

1 Claim.

The present invention relates to a process of influencing the color of tobacco leaves.

It is of great disadvantage in many cases that the shade of tobacco leaves, especially the yellow 5 shades of ripe tobacco leaves which is highly desirable for out goods, in particular fine-cut tobacco and cigaret-tobacco, becomes wholly or in part lost when the leaves are cured for the reason that the latter assume a darker coloration and, in particular, change into brown.

We have now found that the golden-yellow shade of fresh tobacco leaves in their ripened condition can be preserved in a very simple manner by immersing the leaves in water or an aqueous liquid and exposing them to an elevated temperature for a short time. In so doing we have made the surprising discovery that the desired effect is usually already secured in the case of an extremely short. duration of the treatment, so-

that any lowering in extraction of constituents of the is practically avoided.

It has been found that it is advantageous to work in an acid medium; thus, for example, the

water may receive a small addition of acetic acid or hydrochloric acid or any other hydrohalogenic acid, whereas sulphuric acid is of less avail. The effect can still be increased by the addition of agents having a reducing action, preferably those 0 of organic nature, such as formic acid or hydrazine. The simultaneous use of a reducing substance and an acid, as for example an aqueous solution of hydrazine sulphate and hydrochloric acid, also has a favorable action in some cases.

Usually amounts of a few per cent (with reference to the water) of the additional substance are sufficient. In the case of formic acid the desired action, can be effected when using same in a concentration as low as about 1.0 per cent, whereas 40 the other additions stated must be used in a somewhat larger amount.

In order to promote the moistenlng of the leaves with the treating liquid it is preferable to add small amounts of a wetting agent. By this 45 expedient the amount of the reducing or acid additional substances may in many cases be even further diminished.

In choosing the working temperature care should be taken that no valuable constituents are 50 extracted from the vegetable materials. When using water having a temperature of between 90 and 100 C., tobacco leaves have to be immersed for about half a minute in order that the shade thereof be stabilized. When employing a water 56 temperature of about 90 C., any green coloration the quality of tobacco by In Germany plant material October 3, 1935 of the leaves which may still exist at some places will disappear, so that an improvement in the shade is obtained at the same time. In the case of the bulk of the reducing agents and acids which are adapted for the purpose in question it is sufficient toemploy a temperature of about 80 C. and an immersion period of between 5 and 10 seconds.

The possibility of an undesiredlixiviation of tobacco can also be prevented if the treatment of 10 the leaves is, from the very beginning, performed by means of liquids which contain tobacco extract. Together with the stabilization of the shade the material may also be influenced in other respects, for example by adding to the treating bath substances, such as potassium or calcium salts, which influence the burning of tobacco, or such substances as effect a reduction of the nicotine contents or a change of taste, e. g. by a kind of flavoring treatment. 4 20 In many cases, especially when using formic acid as a treating agent, an improvement of the tobacco in taste and odor may also be obtained without the employment of the said known improving agents.

Tobacco leaves gathered in a green condition assume a pale brownish shade suitable for wrappers when using reducing agents or acids.

The process according to this invention has a particularly favorable action when performed subsequent to a treatment with stimulants, such as are employed for forcing vegetables, prematurely interrupting the vegetation rest and accelerating the ripening of fruit. The said pretreatment preferably consists in gas'fying the material with ethylene, ethylene oxide, acetylene, carbon monoxide or nitrous oxide. By the control of the duration of the said pretreatment, any diversity in the shade of the gathered leaves which is due to differences in the state of ripening can be removed. The gasification is interrupted when the bulk of the leaves has assumed a pure golden-yellow coloration or only has but a tinge of green. The said golden-yellow shade is now stabilized by the heat-treatment according to this invention whereby the greenish portions change their color towards yellow.

The leaves thus treated can be dried in any desired manner, for example in the air while hung in drying lofts or other suitable and even'dark rooms, without the danger of impairing the color. The exclusion of light has a favorable rather than a detrimentalaction. Drying the leaves at elevated temperatures is preferably carried out rapidly, preferably by placing them in chambers which have previously been heated up to at least C.

The following table in which some examples are contained, will further illustrate how the invention may be carried out in practice but the invention is not restricted thereto.

Treating Duration Treating liquid temperaof treatture ment- C. Seconds 1 Water 100 30 2 A 2 par cent aqueous solution oi formic acid 80 5 to 10 3 A 2 to 3 per cent aqueous solution of hydrazine hydrate a. 80 5 to' 10 4 A 1.5 to 3 per cent aqueous solution of hydrochloric acid 80 5 to 10 5 A 5 to 7.5 per cent aqueous solution of acetic acid 80 5 to 10 6 An aqueous solution containing 3 per cent oi hydrazine sulphate and 1.6 per thousand of hydrochloric acid 80 5 to 10 2,224,ees

In any 'of the examples listed above there may be added, if desired, wetting agents in an amount of from 0.5 to 1 per thousand, such as condensation products prepared from high molecular fatty acids or their derivatives and aminoor hydroxyalkyl-sulphonic acids. as for example the sodium salt of the taurlde of palmkernel oil fatty acid, or quaternary ammonium compounds which contain high molecular alkyl radicals, as for example dimethyldodecylbenzyl ammonium chloride.

What we claim is: 1

The process of preventing tobacco leaves from becoming brown which comprises dipping the leaves in an aqueous solution of formic acid at a temperature of about 80 to C. for a short time while avoiding extraction.

GEORG PFUETZER. RMANN LOSCH. 

